INFRARED STUDY OF ETHYLENE CARBONATE IN VARIOUS SOLVENTS AND SOLVENT SYSTEMS

The nu-C = O frequency for ethylene carbonate is in Fermi resonance with the first overtone of the skeletal breathing mode, and the extent of Fermi interaction is affected by solvent/solvent interaction. The nu-C = O frequencies have been corrected for Fermi resonance, and the corrected nu-C = O frequencies have been correlated with the mole % CHCl3/CCl4, (CH3)2SO/CCl4, (CH3)2SO/CHCl3, and CHCl3/n-C6H14, the solvent reaction field, and nu-C = O for acetone recorded in the same solvents. Solute/solvent interactions are discussed. The acceptor number of the solvent vs. the nu-C = O frequencies apparently correlates in a different manner for the solvents which form intermolecular hydrogen bonds with the solute. Steric factors are suggested as being one of the reasons that the AN values and nu-C = O frequencies do not give nonambiguous correlations. The nu-C = O mode for ethylene carbonate shifts continuously to lower frequency as the mole % CHCl3 or (CH3)2SO increases in each of the solvent mixtures studied.